Hydrogen has been utilized in various fields in industry. For example, hydrogen has been used as a raw material for production of ammonia by the Harber-Bosch process, production of hydrochloric acid by photoreaction of chlorine gas, modification of fat and oil, such as corn oil and cottonseed oil, by adding thereto for hardening (solidification), and the like; a reducing agent for reduction of a metallic mineral (oxide), production of aniline through reduction of nitrobenzene, catalytic reduction of benzene in production of nylon 66, synthesis of methyl alcohol through reduction of carbon monoxide, desulfurization and the like; and the like.
Furthermore, hydrogen forms no emission other than water on combustion, for example, does not form particulate matters and an exhaust gas including carbon dioxide, and thus is expected as alternate energy, and hydrogen is used as a fuel for internal combustion in a hydrogen vehicle with hydrogen-fueled engine, and is also used as a fuel for a rocket and a fuel cell.
Hydrogen is industrially mass-produced as a by-product of steam reforming and partial oxidation of hydrocarbons (hydrocarbon gas reforming process). In this process, methane gas in natural gas, a paraffin compound, ethylene, propylene or the like is reacted with steam under high temperature with nickel as a catalyst to form hydrogen and carbon monoxide, and by-produced carbon monoxide is further reacted with steam to form carbon dioxide and hydrogen gas. As an alternative method, hydrogen that is formed as a by-product of electrolysis of seawater in the soda industry and the salt production industry may also be utilized.
Hydrogenation reaction where an organic compound is reacted with hydrogen is widely used in organic synthetic chemistry, and many useful compounds are formed by the process. The hydrogenation reaction includes various methods, such as reaction utilizing an alkali metal or the like, reaction utilizing a metal hydride or a metal hydride complex, reaction utilizing diborane or hydrazine, and a reaction utilizing catalytic hydrogenation.
However, the industrial methods for production of hydrogen described above require a large-scale equipment and may not be utilized for convenient production of hydrogen. There is an experimental method of utilizing hydrogen formed by dissolving a metal in a diluted acid or an alcohol, but the problem is that a metal is irreversibly dissolved, and the solution having the metal dissolved therein is necessarily treated.
In the hydrogenation reaction described above, the methods utilizing an alkali metal, a metal hydride, a metal hydride complex, diborane, hydrazine or the like have problems of high cost and hazardous nature of the reaction reagents used, and the method utilizing catalytic hydrogenation is also disadvantageous in that a special metal catalyst is necessarily used.